1. Field of the Invention
The invention relates to turbine engine, such as industrial gas turbine engine or steam turbine engine blade deflection monitoring systems, utilizing an optical camera to capture time-based images of blade position, such as blade tip position. Changes in blade position over time are correlated to blade deflection, which in turn is used by the monitoring system to alarm or stop turbine engine operation if the correlated parameter is out of a permissible operating parameter range.
2. Description of the Prior Art
Industrial turbine engines, such as steam or combustion turbine engines, utilize shaft mounted rotating turbine blades to generate mechanical work, such as for driving an electric generator in a power generation plant and/or compressing air for combustion in a combustion turbine. The compressor or turbine section blades are susceptible to deflection during turbine engine operation, for example due to inlet compression or combustion gas transients or steam backpressure. Permissible blade deflection parameters are often established by turbine engine manufacturers and operators in order to reduce risk of engine damage. An engine blade deflection monitoring system is often employed during new or serviced engine validation to confirm that the engine is operating within permissible blade deflection parameters. In some engine installations a blade deflection monitoring system remains online during some or all engine operation.
Some known turbine engine blade deflection monitoring systems utilize vibration sensors coupled to the engine housing and/or turbine shaft structure to monitor frequency and/or amplitude, which is indirectly attributed to blade deflection. Other known turbine engine blade deflection monitoring systems directly monitor deflection amplitude of one or more individual blades. In some known systems individual blades incorporate strain gauges that measure blade deflection. Other known systems utilize proximity-type sensors that determine one or more blade positions relative to one or more of the proximity sensors. Changes in relative blade position over time are correlated to blade deflection amplitude. Proximity sensors incorporated in individual blade vibration and deflection monitoring systems have included ultrasonic, eddy current, laser and capacitive modality sensors. Individual blade monitoring proximity-type sensors are mounted within the turbine engine internal cavities, where they are exposed to hostile high pressure steamed or combustion gas environments. Exposure of internal sensors to the engine interior's hostile environment increases likelihood that the monitoring system may not remain operational during the entire operating cycle between scheduled maintenance cycles.